The Food and Drug Administration on Wednesday approved an injectable drug in the treatment of a rare group of bone marrow diseases that are often fatal.

The FDA said Dacogen would give another treatment option to people suffering from myelodysplastic syndromes, a condition in which bone marrow does not produce an adequate amount of mature blood cells.

Dacogen, also known as decitabine, is believed to assist normal development of blood cells. The FDA said that about one-fifth of the patients treated with the drug in three clinical trials had a complete or partial response.

The elderly are most prone to having myelodysplastic syndromes. Symptoms include fatigue, weakness, easy bruising, infections, bleeding and fever.

Approximately 7,000 to 12,000 new myelodysplastic syndrome cases are diagnosed in the U.S. each year.